Will Ribbon Work On A Buttercream Cake?

I am doing a wedding cake next weekend. The bride wants a teal ribbon around the borders of the buttercream cake. I am just worried that the ribbon will become stained from the buttercream. How do I avoid this?

You can also rub crisco onto the ribbon before putting it on the cake. The ribbon will be a little darker but it will have an even appearance in color. I have done it several times with colors like red and black. It works like a charm if you don't mind the color being a little darker.